Conventionally, foamed heat-insulating materials to be discarded have been roughly crushed, and buried under the ground or thrown into fire together with other refuse material. In recent years, for environmental protection and resource recovery purposes, investigations have been made into the possibilities for recovering the foaming agents from such foamed material.
It is disclosed in German Patent Document DE 4,016,512 A1, for example, to recovery foaming agents from hard polyurethane foams. In this method, a hard polyurethane foam material is roughly crushed by a crusher and compressed by a cylinder press or the like. A foaming gas is thus discharged from the heat-insulating material, and is absorbed and degassed by an active carbon or the like, to be thus recovered.
However, as a result of experiments made by the present inventors, a hard polyurethane foam heat-insulating material in a volume of 50 mm cubic could not be degassed even by applying of a load of about 5 metric ton (pressure of about 5 metric ton per 25 cm.sup.2). The degassing was thus judged to be practically difficult by a simple compression. The reason for this is that the strength of hard polyurethane foams has been extremely increased in recent years by the enhancement in the quality of resin and the improvement in the manufacturing techniques. Accordingly, it is difficult to degas at the same level by only the compression, both refuse matters generated several decades ago and those generated using the recently adopted manufacturing processes.
The present invention covers the whole recovery system, and is made to solve problems throughout all processes including a pre-treatment process of taking off a foamed heat-insulating material from a refrigerator, a process of degassing a foaming gas, and a post-treatment process for the degassed foamed heat-insulating material. In the pre-treatment process, it is intended to effectively and substantially perfectly peel a foamed heat-insulating material adhered to steel plates and/or plastic material plates constituting a refrigerator using an apparatus improved in labor saving, and to then sort only the peeled foamed heat-insulating material. In the degassing process, it is intended to perfectly degas the foaming gas. Moreover, in the post-treatment process, it is intended to reduce the volume of the fine powder of the resin constituting the foamed heat-insulating material for facilitating subsequent transportation or the like.
The degassing process is more fully described as follows. To degas a foaming gas from a foamed heat-insulating material formed of independent foams, the foam film must be destroyed. The destruction of the foam film by compression requires a high load, as described above. For weakening the destruction strength of the foam film, it is considered to heat the resin of the heat insulating material, however, the heat-insulating material itself has a heat-insulating effect essentially and is difficult to be uniformly heated, which causes the fear that the forming gas is thermally decomposed. On the other hand, it may be considered to cool the foamed heat-insulating material at low temperatures for avoiding the thermal decomposition for making brittle the heat-insulating material; however, the heat-insulating material has a function as a cold insulator essentially, and is difficult to be uniformly cooled.
It is an object of the present invention to provide a method of and apparatus for recovering a foaming gas capable of enhancing a recovery ratio of a foaming gas.
It is another object to provide a system including a method of and apparatus for recovering foaming gas with labor-saving throughout the whole system
According to the present invention, there is provided a crusher supplied with a fragment having foamed material stuck on another material. The crusher peels the foamed material from the other material (e.g., steel plates or plastic plates) of said fragment and forms a mixture of crushed materials containing crushed foamed material and crushed other material. A separator is supplied with said mixture for separating said crushed foamed material from the other crushed material. A recovering device supplied with said crushed foamed material from said separator recovers a foaming agent from said crushed foamed material.
Preferred embodiments of the crusher include a high speed rotor having a plurality of hammers, and a casing having an irregular inner wall surface wherein the foamed heat-insulating material is impact-crushed and grounded.
Preferred embodiments of the separator include a tilting type wind force sorting unit with wind force conveying of the foamed material to an upper conveyor outlet opening while the other solid materials are conveyed downwardly by gravity along a tilting bottom surface of the conveyor unit to a lower conveyor outlet opening. The bottom tilted surface of the wind tunnel section of the sorting unit is inclined at an angle greater than an angle of repose based on the coefficients of friction of the bottom tilted surface and the metal or plastic plates forming the solid material of the mixture. Thus, the plastic or metal slides downwardly under the force of gravity against the upwardly flowing wind force which conveys the foamed material upwardly thereby separating the foamed material from the metal and/or plastic plates.
The recovering device preferably includes a pulverizing device for exerting an external force to the foamed heat-insulating material for destroying independent foams in the foamed heat-insulating material, thereby separating the foamed heat-insulating material into a resin component and a foaming gas within the foam. The recovering device also includes a condensing device for cooling and liquefying the separated foaming gas. A compressor is provided which includes a cylinder having an opening portion of a side surface, a main drive piston with a straight barrel portion having a length longer than that of the opening portion in the axial direction of the cylinder, and a driven piston with a straight barrel portion having a length shorter than that of the main drive piston, the main drive piston and the drive piston being disposed on both the sides of the cylinder while holding the opening portion therebetween, wherein a fine powder of the resin component of the foamed heat-insulating material charged from the opening portion is compressed by movement of the main drive piston on the drive piston side, and at the same time the opening portion of the cylinder is closed by the straight barrel portion of the moved main drive piston, and the compressed fine powder is discharged from the end surface of the cylinder on the driven piston side by movement of the main drive piston and the drive piston on the driven piston side.
A foamed heat-insulating material adhered to plastic or metal material is put in the crusher, and is impactcrushed and ground between a crusher rotor and a crusher casing, thereby peeling the foamed material from the plastic or metal. The mixture of the peeled foamed heat-insulating material and the plastic or metal is then supplied to the tilting type wind force sorter. In this sorter, the planar plastic or metal is slid along the bottom plate of the wind tunnel. The planar plastic or metal pieces are orientated substantially flat and parallel to the wind direction, as a result of which the resistance of the plastic or metal against the wind is significantly reduced. Thus, in terms of the ease of the flying against the wind, a large difference is generated between the plastic or metal and the foamed heat-insulating material. This makes it possible to sort out only the foamed heat-insulating material with a high accuracy. The sorted foamed heat-insulating material is then applied with an external force to destroy individual foams in the foamed heat-insulating material. Accordingly, it is possible to substantially perfectly degas the foaming gas. On the other hand, the fine powder of the pulverized foamed heat-insulating material is charged in the cylinder under the pulverizing portion by the deadweight, and is then compressed and discharged while discharging the foaming gas remaining in the fine powder on the pulverizing portion side.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.